南方基地知识库

Broad emission lines in active galactic nuclei (AGNs) mainly arise from gas photoionized by continuum radiation from an accretion disk around a central black hole. The shape of the broad-line profile, described by D-H beta = FWHM/sigma(H beta), the ratio of full width at half maximum to the dispersion of broad H beta, reflects the dynamics of the broad-line region (BLR) and correlates with the dimensionless accretion rate (M)over dot or Eddington ratio (L-bol/L-Edd). At the same time, Mover dot and L-bol/L-Edd correlate with R-Fe, the ratio of optical Fe II to H beta line flux emission. Assembling all AGNs with reverberation mapping measurements of broad H beta, both from the literature and from new observations reported here, we find a strong bivariate correlation of the form log(Mover dot, Lbol/LEdd) = alpha + beta D-H beta + gamma R-Fe, where alpha = (2.47, 0.31), beta = (1.59, 0.82), and gamma = (1.34, 0.80). We refer to this as the fundamental plane of the BLR. We apply the plane to a sample of z < 0.8 quasars to demonstrate the prevalence of super-Eddington accreting AGNs are quite common at low redshifts.